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Main Authors: Farinhas, António, Guerreiro, Nuno M., Pombal, José, Martins, Pedro Henrique, Melton, Laura, Conway, Alex, Dochat, Cara, D'Eon, Maya, Rei, Ricardo
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2602.00950
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author Farinhas, António
Guerreiro, Nuno M.
Pombal, José
Martins, Pedro Henrique
Melton, Laura
Conway, Alex
Dochat, Cara
D'Eon, Maya
Rei, Ricardo
author_facet Farinhas, António
Guerreiro, Nuno M.
Pombal, José
Martins, Pedro Henrique
Melton, Laura
Conway, Alex
Dochat, Cara
D'Eon, Maya
Rei, Ricardo
contents Large language models are increasingly used for mental health support, yet their conversational coherence alone does not ensure clinical appropriateness. Existing general-purpose safeguards often fail to distinguish between therapeutic disclosures and genuine clinical crises, leading to safety failures. To address this gap, we introduce a clinically grounded risk taxonomy, developed in collaboration with PhD-level psychologists, that identifies actionable harm (e.g., self-harm and harm to others) while preserving space for safe, non-crisis therapeutic content. We release MindGuard-testset, a dataset of real-world multi-turn conversations annotated at the turn level by clinical experts. Using synthetic dialogues generated via a controlled two-agent setup, we train MindGuard, a family of lightweight safety classifiers (with 4B and 8B parameters). Our classifiers reduce false positives at high-recall operating points and, when paired with clinician language models, help achieve lower attack success and harmful engagement rates in adversarial multi-turn interactions compared to general-purpose safeguards. We release all models and human evaluation data.
format Preprint
id arxiv_https___arxiv_org_abs_2602_00950
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle MindGuard: Guardrail Classifiers for Multi-Turn Mental Health Support
Farinhas, António
Guerreiro, Nuno M.
Pombal, José
Martins, Pedro Henrique
Melton, Laura
Conway, Alex
Dochat, Cara
D'Eon, Maya
Rei, Ricardo
Artificial Intelligence
Large language models are increasingly used for mental health support, yet their conversational coherence alone does not ensure clinical appropriateness. Existing general-purpose safeguards often fail to distinguish between therapeutic disclosures and genuine clinical crises, leading to safety failures. To address this gap, we introduce a clinically grounded risk taxonomy, developed in collaboration with PhD-level psychologists, that identifies actionable harm (e.g., self-harm and harm to others) while preserving space for safe, non-crisis therapeutic content. We release MindGuard-testset, a dataset of real-world multi-turn conversations annotated at the turn level by clinical experts. Using synthetic dialogues generated via a controlled two-agent setup, we train MindGuard, a family of lightweight safety classifiers (with 4B and 8B parameters). Our classifiers reduce false positives at high-recall operating points and, when paired with clinician language models, help achieve lower attack success and harmful engagement rates in adversarial multi-turn interactions compared to general-purpose safeguards. We release all models and human evaluation data.
title MindGuard: Guardrail Classifiers for Multi-Turn Mental Health Support
topic Artificial Intelligence
url https://arxiv.org/abs/2602.00950